/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>  
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Brackit Project Team nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.brackit.xquery.node.parser;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

public class RelativeEntityResolver implements EntityResolver {
	private final String baseDir;

	public RelativeEntityResolver(String baseDir) {
		this.baseDir = baseDir;
	}

	@Override
	public InputSource resolveEntity(String publicId, String systemId)
			throws SAXException, IOException {
		if (systemId != null) {
			if (systemId.startsWith("file://")) {
				String targetFile = systemId.substring(7);
				File target = new File(targetFile);

				if (target.exists()) {
					return new InputSource(new FileInputStream(target));
				}
				String curDir = System.getProperty("user.dir");
				if (targetFile.startsWith(curDir)) {
					target = new File(baseDir
							+ System.getProperty("file.separator")
							+ targetFile.substring(curDir.length()));

					if (target.exists()) {
						return new InputSource(new FileInputStream(target));
					}
				}
			}
		}
		return null;
	}
}
